Assuming binita is bonita, then esta prima bonita is: This pretty cousin.
¿Cómo está, bonita? means "How are you, beautiful?"
It means, "You are/she/it is pretty." 'Bonita' is a feminine adjective, so it cannot mean "He is pretty." However, since 'esta' has no accent on the 'a', it could mean 'this', and the phrase, 'this pretty girl/woman'
pretty girl, how are you?
Your wife is so pretty
"¿Cómo es tu hermano?" means "What is your brother like?" "¿Cómo esta tu hemano? means "How is your brother?"
Tienes un hermano in English means have a brother.
It means "the brother".
It means "brother".
Tener un hermano amable is: to have a nice brother.